Polymers are used today in the manufacture of a multitude of products. Their diversity, desirable qualities, and low cost make them excellent substitutes for many natural materials. Unfortunately, due to their open molecular structure and low density, polymers have relatively low cohesion and structural integrity. As a result, polymer molecules are easily pulled out of the polymer during adhesive wear, and the polymer tends to be highly permeable to small molecules, such as oxygen, water, methanol, and lower molecular weight hydrocarbons.
Many applications do not require polymers with high levels of mechanical strength comparable to metals, for example. However, polymers are used in an increasing number of applications that do require elevated levels of mechanical and chemical integrity. An excellent example of such an application is the use of ultra high molecular weight polyethylene to form the "bearing" in a total hip joint replacement.
One way to increase the durability of UHMWPE would be to increase the number of crosslinks between the chains in the polymer. Increased bonding or crosslinking in polymers, generally, should increase the hardness, fracture resistance, softening temperature, and abrasive or adhesive wear resistance of the polymer, and reduce polymer solubility and permeability to small molecules.
The foregoing property enhancements would render polymers more useful in a variety of settings. For example, reduced permeability is important for polymer films, such as nylon and polyethylene terephthalate (PET).
Increasing the hardness, wear resistance, and thermal stability of polymers would be useful in expanding their use for lightweight engine components and plastic window glass coatings in the automotive industry. Nylon and polyethylene terephthalate (PET) are examples of materials that might be suitable for such uses if these properties were enhanced.
Enhancing these properties also would permit more widespread use of low cost polymeric molds for short run, plastic injection molding. Because the polymeric molds, themselves, could be molded, the polymeric molds would be cheaper to make than conventional steel molds.
A method for efficiently and effectively improving the structural integrity and hardness of polymers for select wear surfaces of molded components also would be highly desirable.